<PackageReference Include="Microsoft.AspNet.WebApi.Client" Version="5.2.5-preview1" />

RequestHeaderMapping

public class RequestHeaderMapping : MediaTypeMapping
public string HeaderName { get; }

public string HeaderValue { get; }

public StringComparison HeaderValueComparison { get; }

public bool IsValueSubstring { get; }

public RequestHeaderMapping(string headerName, string headerValue, StringComparison valueComparison, bool isValueSubstring, string mediaType)

public RequestHeaderMapping(string headerName, string headerValue, StringComparison valueComparison, bool isValueSubstring, MediaTypeHeaderValue mediaType)